/*
 * Copyright 2017 StreamSets Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.streamsets.pipeline.api.credential;

import com.streamsets.pipeline.api.StageException;

/**
 * Type for Stage configuration variables using <code>${credential:get(...)}</code> EL functions.
 * <p/>
 * A CredentialValue instance encapsulate the retrieval of credential allowing lazy and refresh retrievals.
 */
public interface CredentialValue {

  /**
   * Returns the credential value.
   *
   * @return the credential value.
   * @throws StageException thrown if the credential value does not exist or if user is not authorized to retrieve
   * the credential.
   */
  String get() throws StageException;

}
